1. Technical Field
The present invention relates to a spine fixation device and, more particularly, to a spine fixation device for vertebral fixation.
2. Description of Related Art
A human spine should resemble a straight line when viewed from the front or back. Scoliosis refers to lateral curvature of the spine and may be inherited or result from a long-term improper body posture or trauma, among other possible causes. A person with scoliosis may have his or her body curved from side to side. In addition to an unsightly body shape, scoliosis tends to cause soreness and pain in the back. If left untreated, scoliosis may lead to degenerative arthritis as a result of uneven exertion of force for a long time. Moreover, an excessively large lateral vertebral curvature may even impair cardiopulmonary functions.
Patients with excessively large lateral vertebral curvatures are often treated by implanting spine fixation devices into the vertebrae from the sides. The spine fixation devices, composed essentially of bone screws and rods, not only prevent the patients' vertebral lateral curvatures from increasing, but also have corrective functions so as to ameliorate the symptoms of scoliosis.
However, a conventional spine fixation device has a large volume and therefore ends up with a large postoperative wound. Furthermore, during implantation of the conventional spine fixation devices, a surgeon must spend a lot of time to ensure that the bone screws and the rods are accurately located and that all the rods are precisely interconnected. In consequence, the operation time is undesirably long.
Taiwan Patent Publication No. M318410 discloses a pivotal connection structure for a fixation frame of a spinal correction device, wherein the fixation frame comprises a fixation carrier, a fixation assembly, and a pivotal connection element. The fixation carrier is formed with an installation hole for receiving the pivotal connection element. The fixation carrier is coupled to an end of a bone screw by means of the pivotal connection element. A rod is fixedly provided in the fixation carrier via the fixation assembly.
According to the disclosure of the above-cited Taiwan Patent Publication, the installation of the pivotal connection element in the fixation carrier allows the fixation carrier to be coupled rapidly to the bone screw, thereby facilitating subsequent installation of the rod, as well as enhancing the efficiency of spinal surgery. When two adjacent rods are not aligned with each other, angular adjustment of the rods is required. However, adjustment of the rods is impossible if the fixation frames are already coupled to the corresponding bone screws. In such a case, complexity of the spinal surgery will be increased. Besides, the problem of large postoperative wounds remains unsolved.